Lifting jack



Dec. 16, 1930. B. F.-JoHN s.N

LIFTING JACK Filed Oct. ll, 1926 fr Ill In .vn l" u .Pun l@ HW IIN HM u lul Il l ml.

wir

eg. standard.

supports the load at its upper end, meshes f the other hand, if the outer screw sleeve is Patented Dec. 16, 1930 irsoxfsTATEs Benin. Jonnson,` or i-teCrnn Wrsoonsriv,

Assreivon 'ro WALKER Manorncrunine CoMriiigr'Ygor naorivn, wisconsin, Av'COn-ronnrron or' wisconsin LIFTING 'JACK Application filed. etober 11, 1926. -Serial No. 140,857.

A This invention relatestofthe class ofdevices known as lifting jacks, and more particularly to a jack of the double extension type, designed to have an exceptionally long lift in proportion to its size and height when in lowered or collapsed position.

While there are innumerable uses for such a jack, it is especially designed for automobiles equipped with the new large size or balloon tires. For this use, it isde'sirable to have a jack which is compact and of small vertical height when lowered,'in order to be placed under the low axle or other `fraine parts when the tire is collapsed, and capable of a comparatively longlift'to elevate the car above its normal driving height in order that the tire may be changed. i

The jack is of that type employing a plurality of screws -telescoping one withinthe other and each contributing its share to the total lift of the j ack. A continuous rotation ofthe driving means will cause the screws to be successively and individually elevated or lowered one at a time. According to the em-v S bodiment of the invent-ion hereshown, two

nested screws are employed, the outer screw being an eXteriorly threaded sleeve which meshes within a nut formed in the rotatable driving gear, which is supported in a hollow rihe inner lifting screw, which within a nut formed in the upper end of the outer screw sleeve. In the operation of this jack, the inner lifting screw will be held from '1 rotation by its engagement with the load. At

this time, if the outer screw sleeve is held against rotation it will be elevatedthrough the rotating driving nut, carrying the inner screw and load bodily upward with it. On

permitted to rotate with the driving member, it will act as a. nut to elevate the inner screw which carries the load.

This present iiiventionjis concerned more if particularly with improvements in the means controlling the rotary and translatory move- `ments of the outer screw sleeve. A yieldable or spring-pressedplunger is mounted in the lower end of the screw sleeve, and is adapted to engage with a vertically extending rib proj ecting inwardly from the wall of the 'standard so as to hold the sleeve against rotation during vits vertical travel, up or down, but this rib terminates short-of the upper and lower ends of the vertical travel of the sleeve so that When at either of these extremities `ofits movement the rib will not interferewith the free rotation of the sleeve andV plunger.` ,Af portion of the wall of the standard orihousing projects inwardly, at both the upper, and

lower ends of the standard, intothe paths of rotation of the yieldable plunger. Each of these projections is formed at one side with a sloping cani .surface adapted to `push back the plunger against its spring, thus permitting the sleeve andV plunger t'o pass the projectiony in this direction of rotation. The other side of the projection isforined with an abrupt stop surface adapted to halt rotation of the plunger Yin the opposite direction. Thesecam projections are positioned, respectively, above and below the ends of the guide ribs, but out of vertical alignmentth'erewithf so as not to interfere with the vertical travel of the plunger when passing up or down the sides of the rib. These cam stopidevices permit continued rotation of the screw sleevein one 'direction only when aty the top of'` its travel, and in the opposite directionv only when at the lowerend of its travel, and,l serve.. to stop rotation in the opposite direction andV guide the plunger back into engagement with rib, all as hereinafter de the vertical guide scribed in detail. l

The general object ofthe invention is Vto provide a jack operating as previously noted above and as set forth in more detail after. l

Another object is to provide novel means for preventing rotation of the outer screw sleeve in one direction when at the upper limit of its travehand in the opposite directionwhen at jthe lower lniit ofv its travel, for' preventing rotation of this screw other times.

Another object is to provide a novel cam delvice cooperating with a spring-pressedplunger to insure the proper reengagement' ofthe plunger with the guide rib inthe standard, 5r

hereinsleeve at all Y members is reversed.

Other objects and advantages of the invention will be more'apparent from the following detailed description of one approved form of the apparatus.

In the accompanying drawings:

Fig. 1 is a central vertical section through the jack,l showing the outer screw at the upper limit of its travel, and the innerscre partially elevated.

Fig. 2 is a horizontal section taken substantially on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section taken substantially'on the line 3-3 of Fig. 1, but showingv the screw sleeve in a partially lowered position. v

Fig. 4 is a horizontal section taken substantially on the line 4-4 of Fig. 1.

The stationary standard for the` jack comprises a substantially cylindrical hollow casting 1, having a broad supporting base 2. Near its upper end the standard has'an inner annular supporting ring or flange 3, and above this a housing 4 partially encloses the driving mechanism hereinafter described. One member 5'of the raceway for the ballbearings 6,l rests upon the flange 3, while the other member 7 of the raceway supports the rotatable nut 8 which is formed integral with the hub of driving beveled gear 9. A short stub shaft 10, journaled in an extension 11 of the housing 4, carries at its inner end a driving beveled pinion 12, which meshes with the beveled drivin@ Gear 9. The outer end of shaft. 10 'is preti/idea with-a socket 13 to cooperate with` any suitable form of removable handle, whereby the jack may be operated from a distance. It will be noted that the shaft. 1() tilts upwardly so that the operators end of the handle `will be elevated to a convenient position.

Since the driving nut 8 supports the lifting screws (hereinafter described), which in turn support the load, the entire load will always be transmitted to the standard 1 through the anti-friction bearings 6, and in this way the driving strain and frictional loss will be reduced to a minimum.

The outer screw 14 is inthe form of a hollow sleeve exteriorly threaded to engage-within the driving nut 8. Pins 15 and 16, inserted between the threads of screw 14 at suitable points, or other equivalent means, en-

gage the bottom and top faces, respectively,

on nut 8 to limit the upward and downward travel of the outer screw 14. An inner screw 17, threaded in the same direction as screw 14,-engages within a nut 18 formed in the upper end of the screw sleeve 14. A loadsupporting cap 19, preferably provided with an upper roughened load-engaging surface 20, isv mounted upon the upper end of inner screw 17. i

'It will now be apparent that if the driving nut 8 is rotated and the screw sleeve 14 is held against rotation, the sleeve will be elevated or lowered through the nut and standard 1, according to the direction of rotation of the nut 8. On the other hand, if the screw sleeve 14 is permitted to rotate 'as a unit with Y the, nut 8, and the inner screw 17 is held against rotation by the load supported thereon, thisinner lifting screw 17 willbe raised or lowered through the rotating nut 18. lVhen the screw sleeve 14 is not rotating, but

` is being raised or lowered by the nut 8, the inner screw 17 and the load supported thereby will be carried bodily up or down with the sleeve'14. vThe mechanism nowabout to be described is designed to control the rotary or translatory movements of the sleeve 14 in accordance with its position of elevation within the standard l, and in accordance with the direction of rotation of nut 8, 4so that the successive movements of the two lifting screws 14 and 17 Vwill take place in a predetermined order. n

Slidably positioned in diametrically opposite openings in the lower end of sleeve 14 is a plunger having an enlarged head 21 adaptedV to serve as a portion of the stop device,

vand a reducedshank 22, about which a spring 23 is compressed between the head 21 and the opposite inner wall of the sleeve. This spring 23 tends to.force the plunger 21 outwardly at all times against the inner wall of standard 1*, although this outward movement may be limited by an enlarged end 24 on the shank 22. A vertically extending guide rib 25 is formed in the bore of standard 1, this rib terminating short of the upper and lower limits of travel of the plunger 21, as best shown in Fig. 1. During the normal upward or downward `travel of' the sleeve 14, the plunger 21 will, after a partial rotation, engage the rib 25 and prevent further rotation of the sleeve. The relative positioningof the plunger and rib when the jack is being loweredis indicated in Fig. 3. When the jack is being elevated, the plunger will engage against the opposite side of the rib 25, as indicated in dotted lines, Fig. 3. Obviously,

when the plunger has passed above or below the respective uppery and lower ends of the rib 25, this guide rib will not interfere with the continuous rotary movement of the plunger 21 and sleeve v14. The wall of that portion of the standard which surrounds the upper path of rotary movement of the plunger 21 is so formed as to project inwardly into the path of the plunger, as indicated at 26 in Figs. land 2. The sides of this projection 26, which are in the path of rotation of the plunger 21 comprise one cam surface 27 which merges into the inner circumference .of the standard, and one abrupt wall 28 adapted to engage the side of the plungerY and hold same from rotation in much llt thesame" manner that`the'rib25 functions throughout the central portions `of the stand.

ard. When the sleeve 14 and plunger 211are rotated in a counter-clockwise directionyas indicated by the arrow in Fi 2, the plunger will ride up on the cam sur ace 27, depressing the plunger against the resistance Aof spring 3, and will then snap over the end of the projection 26, thus not interfering-in any way with the continued rotation of the sleeve 14 in this direction. l-Iowever, if the direc? tion of` rotation is reversed, after a partial rotation the plungerwill come intoengagement with the abrupt face 28 of the projection and continued rotation in this direction will be impossible. In the lower end of ythe standard, beyond the end of rib 25, but olfset laterally therefrom, is formed an inwardly projecting `portion 29 having a cam surface 30 and an abrupt shoulder 31, and being in all respects the same as the projection 28 already described, exceptthat the projections 26 and 29 areoppositely disposed within the stand ard, that is the cam surfaces 27 and 30 run in opposite directions, as will be seen from a comparison of Figs. 2 and 4. The projection 2G will permit rotation of sleeve 14 in a counter-clockwise direction, butprohibit rotation in a clockwise direction, whereas the projection 29 will allow rotation in a clock-` wise direction, but prevent rotation in a coun ter-clockwise direction. j

` Now describing the general operation of the jack we will first assume that the two i screws 14 and 17 are completely nested one within the other, and both within the stand; ard, that is, the j ack is in its completely low-v ered position. Now in order to elevate the jack, the operating crank will be rotated in a clockwise direction, ythus rotating the driving nut 8 in a counter-clockwise direction, as seen from above. The screw sleeve 14 will tend .to rotate with the driving nut 8,' but 4after a partial revolution the plunger 21 will engage the abrupt shoulder 31 of the projection 29 in the lower end of the standard, and further rotation of sleeve 14 will thus be prevented. Due to the engaging threads between the sleeve 14 and nut 8, the sleeve .will now start to move upwardly, this movement continuing until the plunger 21 has passed up and oil from the shoulder 31. The sleeve 14 will now again rotate with the nut 8 through a partial revolution until the plunger 21 engages with the rib 25, as indicated in dotted lines in Fig. 4. The rim 25 will now hold the screws from rotation until the sleeve 14 has reached the upper limit of its travel, at which time the plunger 21 will run olf from the upper end of rib 25. At this time the pin 15 will engage with the lower face of nut 8 and prevent further upward movement of the sleeve. The driving nut 8 and sleeve 14 will now commence to rotate as a unit (still in a counter-cloclrwise direction), as indicated in Fig.

2. iOnce` during each rotation, the plunger 21 will ride up the cam surface 27 and snap over the projection 26, but obviously this will not vinterfere with the continuous rotation of the parts in this direction. Since the inner screw 17 is heldfrom rotation by the engagement ofthe supporting cap 19-.with the load, the now rotating nut 18 in the upper end of sleeve '14 will cause the inner screw 17 to be projected upwardly through the hollow screw sleeve 14. This movement will continue until the stop pin 32 in the lower end of screwl 17 engages the lower face of nut 18, thus v.limiting the upward extension of the jack.

ln order to lower the ack, the direction of rotation of the operating handle is reversed, thus'causing thedriving nut 8 to rotate in a clockwise direction, as seen from above. For a partial rotation the sleeve 14 will rotate witht-he nut 8, thus bringing the plunger 21 into engagement with the abrupt face 28 ofprojection 26. rlhis will prevent further rotation of the sleeve 14 vwhich will now move downwardly through the driving nut 8. As soon as the plunger 21'has passed below the stop shoulder 28, it will rotate through a partial revolution until it comes into engagement with the guide rib 25, which will prevent further rotation of the screw sleeve 14 during the lowering movement of the sleeve. rlliis position of engagement is shown' in Fig. 3. During this portion of the operation, there will be no relative movement between the two screws 14 and 17, but the inner screw 17 will be carried 4bodily downward by the screw sleeve'14. The downward movement of sleeve 14 will be limited bythe engagement of pin 16 with the upper surface of driving nut 8, and at this time the plunger 21'will pass beneath the lower end of rib 25 and the sleeve will be free'to rotate with the driving nut, lts-continued rotation in this clockwise directionwill not be prevented by the projection 29 at the lower end of the standard, since the plunger will simply run up the cam surface 30 and snap over the projection 31, once during every revolution of the sleeve. However, when the direction of rotation of the operating crank is reversed, the plunger 21 will engage with the shoulder 31, and the elevating operation will commence, as already described-hereinabove.

The' controlling stop-devices comprising the spring pressed plunger and the cooperating cams in theends of the standard insure a definite order of movement of the two lifting screws, compelling the screw sleeve 14 to move upor down iirst in either direction, Y

whether or not there is any load carried by the jack.` Also, these stop devices are so lowhen the translatory movement of the sleeve begins.

It will be noted that the plunger 21 passes up along one side of rib 25 when the jack is elevated, and down along the other side when the jack is lowered.V The cam projections 26 ribs may be easily cast directly in the` standrfi ard which houses and supports the movable parts of the jack.

I claim:

1. In a lifting jack comprising a standard, and a lifting member capable of either vertical or rotary movements in the standard,

means for controlling the movements of the lifting member comprising a yieldable plunger projecting from the member, a substantially vertical guideribV in the Vstandard adapted to engage the plunger and prevent Y continued rotation of the member, the rib terminating shortof the limit of vertical movement of the member, and means carried by the standard beyond the end of the rib but entirely out of vertical alignment therewith for engaging the plunger to preventcontinued rotation in one direction,v this means serving to depress the plunger to permit continued rotation of the plunger in the opposite direction.

2. A lifting jack comprising a standard, a pair of telescoping lifting screws, a rotatable driving member in which the outer screw is threaded, a spring-pressed plunger mounted in and projecting laterally from the lower end portion of the outer screw, a substantially vertical guide rib in the standard for engaging the plunger to prevent continued rotation thereof, the rib terminating short ofthe ends of the path of Vertical travel of the plunger whereby the plunger may rotate freely in paths positioned beyond the ends of the rib, and projections formed on the inner walls of the standard and extending into said paths of rotation of the plunger, said projections each having a cam surface on one side and a stop shoulder on the other sideand being entirely out of vertical alignment with the rib whereby the plunger may pass freely beyond the endsof the rib without ,i engaging the projections, the cam surfaces and stop shoulders being oppositely disposed respectively on the two projections whereby the plunger may rotate continuously in one direction only when beyond the upper end of the rib, and in the opposite direction only when below the lower end of the rib.

3. A lifting jack comprising a standard, a

pair of telescoping lifting screws, a rotatable.

driving member in which the outer screw is threaded, a spring-pressed plunger mounted in and projecting laterally from the lower end' portionof the outer screw, a substantially' vertical gui'derib in the standard for engag- -with the rib whereby the plunger may pass freely beyond the end of the rib into its path of rotation without engaging thefprojection, said cam surface serving to' depress the plunger and permit continued rotation of the plunger in one direction and said 'stop shoulder serving to engage the plunger and prevent continued rotation thereof in the other direction,r

Li. A lifting jack comprising ay standard, a pair of telescoping lifting screws, a rotatable driving member in which the outer screw is threaded, a yieldable plunger mounted in and projecting laterally from the lower end portion of the outer screw, a substantially vertical guide rib in the standardffor engaging the plunger toprevent continued rotation thereof, the rib terminating short of the one end of the path of vertical travel of vthe plunger whereby the plunger' may rotate freely in a path beyond this end of the rib, and a projection formed on the inner wall of the standard and extending into this path of rotation of the plunger, said project-ion having a cam surface on one side and a stop shoulder on the other side and being positioned entirely out of vertical alignment with the rib whereby the plunger may pass freely beyond the end of the rib into its path of rotation without engaging the projection, said cam surface serving to' depress the plunger and permit continued rotation of the plunger in one direction and said stop shoulder serving to engage the plunger and prevent continued'rotation thereof in the other direction.

BEN F. JOHNSON. 

